Annealing box



. June 2, 1931. NlsBET 1,808,314 I ANNEALING BOX Filed May 124, 1929 5 Sheets-Sheet l gmnto'u mama June 2, 9 I G. BQNIsBE'r 1,808.3 14

' ANNEALING BOX I A File& May 24, 1929 s sheets-sheet s TE M R DEGREES, FA HR.

50 4:: ma nv FURNACE 01.11 TYPE ANNEALING T uvuourrs Box h F IE... 5

IN'HOURS NEW TYPE ANNEL/Nd TIME IN FURNACE. '1

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Patented June 2,1931 i v -.1,ss,314

UNITED STATES PATENT OFFICE,

GEORGE 3. 1118331, OI CLEVELAND, OHIO, ASSIGNOR TO THE OTIS STEEL ('JOII'A NY,

O1 CLEVELAND, OHIO, A CORPORATION 01 OHIO HEALING BOX Y Application filed Kay 24,

This invention relates to an annealing box such as may, contain a pack of sheet metal in an annealing furnace. The object of the invention is to provide for the more uniform heatingof the contents of the box and also to increase the strength and stiffnessof the box bottom, furnace heat.

. It has been customary to provide annealing boxes with solid flat bottoms on which a' ile of metal sheets rests. It has been found owever, that with such boxes it is very dilficult to satisfactorily" anneal the sheets near the bottom of the ile without overannealing the sheets nea'r t e top. Not only do the sheets near the bottom fail to receive the desired amount of heat, but the bottom of the top and bottom of the box and at the same time stiffen. the bottom, by providing the s bottom with u wardly facing ribs or projec- .tions. '-These eave horizontal flues. beneath p the ack of sheets, enabling a circulation of the eating ses beneath and around the metal sheets fi uring annealin ribs add strength and stifi'en fire bottom and greatly reduce the tendency to warping.

My invention is illustrated in the drawings hereof and is hereinafter more fully described, and the essential novel features are summarized in the claim.

partly broken away, of an annealing box embodying m invention; Fig. 2 is a crosssection thereo showing a pack of sheets within the box; Fig, 3 is a perspective of a portion of the box bottom with a portion of a pack of .sheets thereof Fig. 4 is a fragmentary crosss'ection of the bottom taken at right angles to the ribs; Fig. 5 is a diagram illustrating the heating of the top and bottom portions of the pile in the ordinary flat-bottom box; Fig. 6 1s a similar diagram illustrating the heatin of the same parts of the pile in my improve b0 x. In Figs. 1 to 4, 10 indicates the bottom of preventing its warping in the These same In the drawings Fig. 1 is a perspective,

192p. Serial No. 368,814.-

the box having outwardly formed stifiening corrugations or ribs 21 and being adapted to rest on the bottom of. the box within the boundary wall 11in the usual manner. In Figs. 2, 3 and 4 I have shown, on the upper surface of the. ox-bottom 10, parallel upstanding ribs 12. These ribs are shown as arranged in two sets with an aisle space 13 between them. The ribs are preferably integral with the bottom 10 and erg'e therewith by suitable'fillets '14. The ribs have their top surface 15 all in a single plane parallelwith the general plane of thebottom 10. Suitable smooth'aisle spaces 16' are provided on the bottom beyond the ends of the ribs and adj acent the boundarywell 11. The to rests I on this smooth marginalportion and t. ere is a clearance between the inner side of the cover and the ends of th ribs, so that the cover may be easily put in 11sec. J

find that the warpingcan be best prevented by making the ribs diagonal, that is, extending at an angle at about to the sides, and it is so shownin Fig. 3. When so directed each rib is effective in resisting distortion of the bottom abouteither a transverse axis or a longitudinal axis. 1' have shown oneaisle space 13 extending longitudinally of the bottom between the sets of ribs, but more than one such space may be provided if desired. It is useful in obtaining a more even distribution of the gases beneath the pack of sheets.

The pile of sheets indicated by A in Figs. 2 and 3 stands on the top surface 15 of the ribs. It will be seen that the spaces between these ribs provide a lar e number of fines for the passage of gases beneath the pile of sheets between the aislespaces at theeenter and beyond the outer ends of the ribs. Expe-' rience has demonstrated that by this means the bottom portion of the pile is heated to very nearly the same extent as the top portion, resulting in a substantially uniform an nealing of the entire pile.

The diagrams Figs. 5 and 6, illustrating the difierent heating action of the old and new type of boxes are plotted from actual tests made by the use of suitably placed 2 1,eoa,a14

thermo-couples over a period of approxiaisle' space providing a longitudinal flue for mately forty-two hours. In these views the furnace temperature is indicated by the line F; the temperature of the pack of sheets adjacent the top thereof by the line T, and the temperature of such pack a short distance above the bottom by the lineB.

It will be seen from Fig. 5, that when the furnace heat was turned on at approximately 1000 F., the stack of sheets began to heat at once, with the sheets near the top heating much more rapidly than those near the bottom. The two curves T and B, it will be seen, diverged for many hours of heating. After about ten hours the furnace heat was maintained substantially uniform, as indi cated by the line F, for about twenty hours. During that time the curve T continued to be a very considerable distance above the curve B. At the end of thirty hours the heat was shut ofi. Shortly thereafter the temperature at the top .of the pack began to drop while the temperature at the bottom rose slightly, so that the two curves gradually approached each other and were nearly the same atthe time of withdrawal. Now such divergence in temperature between the top and bottom portions during the larger portion of the operation results in either the gases;

signature.

bottom sheets underannealing or the top sheets overannealing.

Fig. 6 indicates the conditions within my improved annealing box. Here the furnace temperature is substantially the same as before, but the curve'B, representing the temperature of the pack near the bottom has been materially raised, while the curve T representing the temperature of the pack near the top as been materially lowered so that the two temperatures run very close to each other throughout the whole operation, be coming identical a few hours after the heat is shut off and being close to each other at the end of the operation. Experience has demonstrated that with my box substantially perfect annealing is obtained throughout the'entire pack of plates, the uniformity being such that after removal the plates are in substantially identical condition.

The continued heat to which annealing boxes are subjected tends to cause the parts to warp. This is not troublesome in the top but has been very unsatisfactory in the bottom as 'it prevents the forming of even support for the pack of sheets. With my invention however, the ribs so strengthen and stiffen. the bottom that the warping is avoided.

I claim A bottom for an annealing box comprising a horizontal member having integral parallel ribs extending upwardly from the bottom of the box, said ribs extending diagonally in a plurality of sets separated by an GEORGE B. NISBET.

In testimony whereof, I-hereunto ailix my 

